The Magellanic squall: gas replenishment from the Small to the Large Magellanic Cloud

Abstract

Abstract We first show that a large amount of metal-poor gas is stripped from the Small Magellanic Cloud (SMC) and falls into the Large Magellanic Cloud (LMC) during the tidal interaction between the SMC, the LMC and the Galaxy over the last 2 Gyr. We propose that this metal-poor gas can closely be associated with the origin of the LMC's young and intermediate-age stars and star clusters with distinctively low metallicities with [Fe/H]< −0.6. We numerically investigate whether gas initially in the outer part of the SMC's gas disc can be stripped during the LMC–SMC–Galaxy interaction and consequently can pass through the central region (R < 7.5 kpc) of the LMC. We find that about 0.7 and 18 per cent of the SMC's gas could have passed through the central region of the LMC about 1.3 Gyr ago and 0.2 Gyr ago, respectively. The possible mean metallicity of the replenished gas from the SMC to LMC is about [Fe/H]=−0.9 to −1.0 for the two interacting phases, if a steep metallicity gradient of the SMC's gas disc is assumed. These results imply that the LMC can temporarily replenish gas supplies through the sporadic accretion and infall of metal-poor gas from the SMC. They furthermore imply that if this gas from the SMC can collide with gas in the LMC to form new stars in the LMC, the metallicities of the stars can be significantly lower than those of stars formed from gas initially within the LMC.